Generally, a liquid crystal display (LCD) is display device that is able to display desired images by transmitting a data signal to each of pixels arranged in a matrix type according to image information and adjusting light the transmissivity of the pixels. Such the LCD may not be self-light emitting and a back-light unit is installed to a backside of the LCD to present the image.
A plurality of supporting parts may be provided in the back-light unit to support an optical sheet and to keep surface flatness of the optical sheet such that air cavity of the back-light unit may maintain a predetermined height to maintain light uniformity.